A damper device structured to open and close an opening part structuring a part of a cold air passage of a refrigerator by a baffle is described in Japanese Patent Laid-Open No. 2003-240102. A baffle of the damper device described in the document is turned by a stepping motor and a drive mechanism including a gear train. The baffle is moved between a closed position closing an opening part and an open position opening the opening part. The gear train includes a partially toothless gear and a sector gear which is driven by the partially toothless gear.
The partially toothless gear is provided with an outer peripheral part having an outer peripheral face along a tooth tip circle of a teeth part at a portion adjacent to the teeth part in a circumferential direction. A length in an axial line direction of the outer peripheral part is shorter than a tooth width of the teeth part, and the outer peripheral part is provided with an end face facing one side (upper side) in the axial line direction at a midway position in the axial line direction of the teeth part. The sector gear is provided with a first tooth whose portion facing the outer peripheral face of the outer peripheral part of the partially toothless gear is cut out and capable of entering to an inner peripheral side of the tooth tip circle on one side (upper side) in the axial line direction of the end face of the outer peripheral part. Further, the sector gear is provided with a second tooth which is disposed at a position adjacent to the first tooth and is capable of abutting with the outer peripheral face of the outer peripheral part when the first tooth is entered to the inner peripheral side of the tooth tip circle. The sector gear is an output gear and is connected with the baffle.
In a state that the baffle is located at a closed position and the partially toothless gear is stopped, the first tooth of the sector gear is entered to the inner peripheral side of the tooth tip circle on one side in the axial line direction of the end face of the outer peripheral part. Further, the second tooth of the sector gear is abutted with the outer peripheral face of the outer peripheral part. In this case, when the second tooth is abutted with the outer peripheral part, the sector gear is prevented from turning in an opening direction of the baffle due to abutting with the outer peripheral part. Therefore, in the damper device described in Patent Literature described above, the baffle located at the closed position is prevented from moving to an open position.
FIG. 8A is a perspective view and FIG. 8B is a plan view showing a partially toothless gear and a sector gear which are capable of being utilized in the gear train of the baffle drive mechanism in the above-mentioned Patent Literature. In FIGS. 8A and 8B, a partially toothless gear 38 is provided with a circular arc-shaped outer peripheral part 52 having an outer peripheral face 52a having the same diameter and being concentric with a tooth tip circle 51a of a teeth part 51 at a portion adjacent to the teeth part 51 in a circumferential direction. In a sector gear 39, a tooth (first tooth 68) disposed at one end in a circumferential direction is provided with a cut-out part in a portion which faces the outer peripheral face 52a of the circular arc-shaped outer peripheral part 52 of the partially toothless gear 38.
FIGS. 8A and 8B show states that a baffle is located at a closed position and the partially toothless gear 38 is stopped. In this state, a first tooth 68 of the sector gear 39 is entered to an inner peripheral side of the tooth tip circle 51a on one side (upper side) of an end face 52b of the circular arc-shaped outer peripheral part 52 in a turning center axial line “L1” direction of the partially toothless gear 38. Further, a second tooth 69 of the sector gear 39 is abutted with an outer peripheral face 52a of the circular arc-shaped outer peripheral part 52. In this manner, the sector gear 39 is prevented from turning in a first turning direction “B1” (turning direction of the baffle for opening).
When the baffle located at the closed position is to be moved to an open position, the partially toothless gear 38 is turned in a first turning direction “A1” by driving a stepping motor. Therefore, when the partially toothless gear 38 starts turning, the tooth 53 (tooth on a front end in the first turning direction “A1”) disposed on the most circular arc-shaped outer peripheral part 52 side of the partially toothless gear 38 is passed through the second tooth 69 of the sector gear abutted with the outer peripheral face 52a of the circular arc-shaped outer peripheral part 52 and is engaged with the first tooth 68.
In this example, as shown in FIGS. 8A and 8B, when the turning center axial line “L2” of the sector gear 39 is inclined due to force acted on the sector gear 39 by the baffle, component tolerances and the like, an end 69c on one side (upper side) in the axial line “L1” direction of the second tooth 69 of the sector gear 39 in the abutted state with the outer peripheral face 52a of the circular arc-shaped outer peripheral part 52 may be entered to an inner peripheral side of the tooth tip circle 51a of the partially toothless gear 38 on the one side in the axial line “L1” direction on the end face 52b of the circular arc-shaped outer peripheral part 52. In this case, when the tooth 53 of the partially toothless gear 38 is going to pass through the second tooth 69 of the sector gear, the tooth 53 of the partially toothless gear 38 and the second tooth 69 are interfered with each other to generate abnormal noise.